<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div style="width:100px;height:100px;background-color:pink;"></div>
</body>
<script>
    let box = document.querySelector("div");
    console.log(box);
    box.style.backgroundColor = 'green';
    // 对象.元素 = 值  有值则是修改，没有为赋值
    box.style.width = '10px';
</script>

</html>